1. Field of the Invention
The present invention relates to CRT (Cathode Ray Tube) devices used for TVs and computer displays, and deflection yokes used in such CRT devices, particularly to the structures of the deflection yokes.
2. Description of the Related Art
There is a type of deflection yoke that comprises what is called a slot core. A slot core denotes a type of a funnel-shaped ferrite core that has, on the inner wall thereof, a plurality of slots each of which extends from the narrower end to the wider end, the plurality of slots being arranged circumferentially. A vertical deflection coil and a horizontal deflection coil are wound so as to be guided by the slots of the ferrite core.
A deflection yoke with such an arrangement has the following advantageous effects over a deflection yoke including a ferrite core that is simply funnel-shaped and has a smooth inner wall: The deflection sensitivity is improved because it is possible to position the ferrite core closer to the cathode ray tube. Also, it is possible to reduce eddy-current loss and inhibit heat generation of the deflection yoke because the magnetic flux is less likely to have a flux linkage with the deflection coils.
One of the problematic issues concerning a deflection yoke to which a slot core is applied is how to provide insulation between the vertical deflection coil and the horizontal deflection coil while maintaining the productivity in the manufacturing of deflection yokes. To be more specific, in a case of a ferrite core that is simply funnel-shaped, the vertical deflection coil and the horizontal deflection coil disposed inside can be insulated by inserting, between those coils, an insulating frame that is simply funnel-shaped likewise. On the other hand, in a case of a slot core, since the vertical deflection coil and the horizontal deflection coil are wound so as to be disposed in each of the slots, insulation cannot be provided so simply as that.
One of the examples that have solved the aforementioned problem is a deflection yoke disclosed in the Japanese Unexamined Patent Application Publication No. 11-7891. In this deflection yoke, a funnel-shaped insulating frame as a whole is formed with ridges and slots to fit the ridges and slots in the slot core. Then, after winding a vertical deflection coil directly into the slots of the slot core, the aforementioned insulating frame gets fitted into the slots of the slot core. Subsequently, a horizontal deflection coil gets wound into the slots on the inner wall of the insulating frame. According to this arrangement, there is no loss in the productivity because the insulation between the deflection coils is made by a very simple operation of fitting, onto a slot core, an insulating frame that is shaped to fit the slots of the slot core, after a vertical deflection coil is wound.
Another problematic issue concerning a deflection yoke to which a slot core is applied is how to obtain a deflection magnetic field distribution as desired. This issue arises from circumstances as follows: In a case of a slot core, since the deflection coils are wound along the slots as mentioned above, the winding pattern of a deflection coil which determines the deflection magnetic field distribution is restricted by the ridges and slots (the slot pattern) of the slot core. This is because a slot core (a ferrite core) has a little flexibility in formation of a slot pattern due to its manufacturing process. The deflection yoke disclosed in the aforementioned Japanese Unexamined Patent Application Publication No. 11-7891 has a little flexibility because the winding pattern of not only the vertical deflection coil that is wound directly on the slot core, but also of the horizontal deflection coil, as a result, is restricted by the slot pattern of the slot cores.
In order to cope with this second problematic issue, a deflection yoke is disclosed in the Japanese Examined Utility Model Application Publication No. 7-35289, for example. A funnel-shaped ferrite core used in this deflection yoke has slots formed only in the area of the narrower half, and the inner wall of the wider half is smooth without ridges or slots, so that the flexibility of winding pattern can be achieved in the wider half; however, the Japanese Examined Utility Model Application Publication No. 7-35289 fails to disclose an insulating means between the deflection coils, let alone specific guiding means for the deflection coils.